1. Field of Invention
The present invention pertains to the field of distributed systems. More particularly, this invention relates to power distribution to nodes in a distributed system.
2. Art Background
Distributed systems such as distributed control systems are commonly arranged as a collection of nodes which are interconnected via one or more network communication links. The network communication links may be arranged using one or more intervening communication devices such as repeaters, switching hubs, or gateways. Nodes that are interconnected via network communication links may be referred to as remote nodes.
One prior method for providing electrical power to remote nodes is to route dedicated power lines throughout the distributed system to the remote nodes. Unfortunately, the routing of dedicated power lines usually increases the cost installing and maintaining a distributed system.
Another method for providing power to remote nodes is to provide each remote node with its own power supply such as a battery or a power supply driven by an AC power source. Unfortunately, providing each remote node with its own power supply usually increases the cost of each remote node and increases the overall cost of a distributed control system.
Another method for providing power to remote nodes is to superimpose the signaling required for communication with the remote nodes onto the conductors that supply power to the remote nodes. Unfortunately, such a method usually increases the cost of the remote nodes. In addition, such a method usually increases the complexity of the communication circuitry in the remote nodes and may limit performance.
A system is disclosed in which remote nodes are supplied with electrical power using existing network communication links. A communication device in a system according to the present techniques routes electrical power to a remote node via a set of unused lines of a network communication link used for communication with the remote node. The electrical power distributed to the remote nodes may be AC or DC power. The system routes electrical power to remote nodes via a set of lines in the same cable bundle as communication signal lines. This saves wiring costs and installation costs.
Other features and advantages of the present invention will be apparent from the detailed description that follows.